Holocene subsurface temperature variability in the eastern Antarctic continental margin
We reconstructed subsurface ($45-200 m water depth) temperature variability in the eastern Antarctic continental margin during the late Holocene, using an archaeal lipid-based temperature proxy (TEX 86 L). Our results reveal that subsurface temperature changes were probably positively coupled to the variability of warmer, nutrient-rich Modified Circumpolar Deep Water (MCDW, deep water of the Antarctic circumpolar current) intrusion onto the continental shelf. The TEX 86 L record, in combination with previously published climatic records, indicates that this coupling was probably related to the thermohaline circulation, seasonal variability in sea ice extent, sea temperature, and wind associated with high frequency climate dynamics at low-latitudes such as internal El Niño Southern Oscillation (ENSO). This in turn suggests a linkage between centennial ENSO-like variability at low-latitudes and intrusion variability of MCDW into the eastern Antarctic continental shelf, which might have further impact on ice sheet evolution.
(Geophysical Research Letters. vol. 39, n° 0094-8276, pp. L06705, 28/10/2026)
NIOZ, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, AWI, VU, NIOZ
Recovery potential of periphytic biofilms translocated in artificial streams after industrial contamination (Cd and Zn)
Metal wastes can significantly disturb aquatic communities, particularly photosynthetic organisms, the main primary producers in freshwater running ecosystems. In this study, biofilms and diatoms were used as bioindicators to characterize the kinetics of biofilm recovery. An experimental decontamination study was conducted under laboratory conditions, after biofilm colonisation at a site subject to discharge of industrial metals (Zn and Cd) and in parallel at an upstream site, metal-free, considered as a control. After 24 days of colonisation, biofilms were translocated and maintained in the laboratory for 56 days under clean conditions (control and decontamination) or metal contamination. Various tests were conducted from the community level—measures of metal bioaccumulation, cell densities and taxonomic investigations, to the individual level—measures of teratological forms. After 56 days of decontamination, Zn and Cd concentrations in decontaminated biofilms showed a sharp decline, respectively ranging from 6.7 ± 2 to 4 ± 2.5 mg Zn g-1 DW and from 207.6 ± 24.5 to 45.4 ± 9.9 lg Cd g-1 DW. However, at the end of the experiment bioaccumulations remained significantly higher than concentrations in control biofilms. Despite a diatom evolution in biofilm assemblages, taxonomic inventories did not demonstrate a complete restoration of diatom communities in biofilms under decontamination conditions compared with controls, since metal-resistant species initially present after colonisation at the contaminated site, such as Eolimna minima, persisted in high abundance in decontaminated biofilms. Biofilms kept under metal pressure showed very high bioaccumulation capacities and a sharp decline of species diversity which allowed identification of some resistant species. Regarding these first results on the behaviour of diatom biofilms under experimental decontamination conditions, improvement of the natural hydrosystem’s chemical state appears quickly, but an eventual return to good ecological status appears delayed, with the persistence of metal-tolerant species even after 56 days.
(Ecotoxicology. vol. 21, n° 0963-9292, pp. 1403-1414, 28/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CNRS, UR REBX, IRSTEA
Increase of marine juvenile fish abundances in the middle Gironde estuary related to warmer and more saline waters, due to global changes
Estuaries have an essential ecological function for several marine fish species, that use these systems as nurseries. Previous studies in the Gironde estuary have reported an increase in water temperature and an extended seawater intrusion associated to global changes. In this study, we evaluated whether these changes impact the nursery function in the middle part of the system, based on the analyses of long-term data series (1991e2009) collected in that area. Trend analysis, correlations and generalized additive models (GAM) were computed in order to study the influence of water temperature and salinity changes on marine juveniles occurrence/densities. Results showed that densities of all the studied species (i.e. Engraulis encrasicolus, Sprattus sprattus, Dicentrarchus labrax, Solea solea, Argyrosomus regius, Merlangius merlangus) significantly increased over the period considered. Changes in water temperature and seawater intrusion contributed to explain the variability in presence/absence and in densities of the majority of these species. However, the deviance explained by GAM and the relevance of these two explanatory variables differed considerably according to species. For most species, it was suggested that the interaction of these two factors, and their effects on other variables, may explain the increase in abundance in the middle part of the Gironde. The effects of global changes in this estuarine system may favour its nursery function for marine juveniles, but some evidence of effects at a wider scale (community and ecosystem levels) may alter the structure and functioning of this system.
(Estuarine, Coastal and Shelf Science. vol. 104-105, n° 0272-7714, pp. 46-53, 28/10/2026)
UR EPBX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ULISBOA
Monitoring and indicators in port. Development of HFNI Valvometry for the online assessment of ecological potential. Portonovo : present and future of port water quality management in the EU Atlantic Area
(28/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LMBA, UBS, UBO EPE, CNRS
Mass wasting processes along the Owen Ridge (Northwest Indian Ocean)
The Owen Ridge is a prominent relief that runs parallel to the coast of Oman in the NW Indian Ocean and is closely linked to the Owen Fracture Zone, an 800-km- long active fault system that accommodates today the Arabia-India strike-slip motion. Several types of mass failures mobilizing the pelagic cover have been mapped in details along the ridge using multibeam bathymetry and sediment echosounder. Here we present a synthetic map of the different types of mass wasting features observed along the ridge and we further establish a morphometric analysis of submarine landslides. The spatial variation of failure morphology is strongly related to the topography of the basement. The highest volumes of multi-events generated slides are mobilized along the southern portion of the ridge. There, the estimated volume of evacuated material during a slide is up to 45 km3. Combining these new observations with re-interpreted ODP seismic lines (Leg 117) documents sporadic mass wasting events through time along the southern segment of the ridge since its uplift in the Early Miocene, with a typical recurrence rate of the order of 105-106 years. Although seismicity may still be the final triggering process, mass wasting frequency is mainly controlled by the slow pelagic sedimentation rates and hence, time needed to build up the 40-80 m thick pelagic cover required to return to a mechanically unstable pelagic cover .
(Marine Geology, n° 0025-3227, pp. 1-21, 28/10/2026)
iSTeP, UPMC, CNRS, LGENS, INSU - CNRS, CNRS, ENS-PSL, PSL, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
A new breaking wave height direct estimator from video imagery
Breaker height is a key parameter of nearshore processes and the demand for a continuous remote estimator is pressing. In this paper we present a standalone remote video-based method that estimates wave height at the breakpoint. Individual breaking events are first identified from changes in optical properties and wave height is further derived from the optical signature at the onset of breaking. An extended validation is performed using a dense wave basin dataset. The results show the ability of the method to measure individual breaker heights (9% of mean error, 18% RMS). In addition, the unique combination of in situ and remotely sensed data allows the estimation of two other breaking-related parameters, the height-to-depth ratio and wave front face slope, which show a substantial amount of dispersion. Because nearshore video systems are rapidly spreading over world coasts, this low-cost remote breaker height estimator should encounter large interest in coastal engineering studies.
(Coastal Engineering. vol. 61, n° 0378-3839, pp. 42-48, 28/10/2026)
PUC, LEGOS, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, UTFSM, LEGI, UJF, Grenoble INP, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Probabilités des évènements rares sur des séries temporelles environnementales
(28/10/2026)
LMBA, UBS, UBO EPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LIMATB, UBS, UBO EPE, IBNM, UBO EPE
Seasonal succession of estuarine fish, shrimps, macrozoobenthos and plankton: physico-chemical and trophic influence. The ironde estuary as a case study
Characterization of the structure and seasonal variability of biotic communities is essential for a better understanding of estuarine ecosystem functioning and in order to manage these highly fluctuant and naturally stressed systems. Numerous studies have investigated the role of environmental factors in controlling temporal variations in biotic communities. However, most have concluded that the explanatory power of physico-chemical variables was significant but not sufficient to explain ecological dynamics. The aim of the present study was to put forward the importance of trophic interactions as an additional structuring factor of species seasonal variability by examining simultaneous dynamics of all estuarine biotic communities, with the example of the oligo-mesohaline area of the Gironde estuary (SW France) as a case study. Data on the main biological groups (fish, shrimps, macrozoobenthos and plankton) sampled during a five-year period (2004-2008) at monthly intervals using a well standardized protocol, as well as data on environmental variables, were compiled here for the first time. According to species composition, results indicated that the Gironde estuary is used as a nursery, feeding, resident and migratory habitat. Results showed that, for almost all species, strong seasonal fluctuations occurred with a succession of species, indicating an optimization of the use of the available resources over a typical year by estuarine biological communities. Multivariate analyses discriminated four seasonal groups of species with two distinctive ecological seasons. A clear shift in July indicated a biomass transfer from a “planktonic phase” to a “bentho-demersal phase”, corresponding to spring and summer-autumn periods, respectively. In regard to the temporal fluctuations of dominant species of all biological groups, this study highlighted the possible influence of trophic relationships, predation in particular, on seasonal variations in species abundance, in addition to the physico-chemical influence. This study enabled us to synthesize crucial seasonal data and to discuss their integration into seasonal models of estuarine functioning and/or specific prey-predator models. In a global change context, prey abundance variations could generate changes in the temporal dynamics of their predators (and conversely), and potentially in the functioning of the whole estuarine system.
(Estuarine, Coastal and Shelf Science. vol. 112, n° 0272-7714, pp. 243-254, 28/10/2026)
UR EPBX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Barred-beach morphological control on infragravity motion
A conceptual analysis of the coupling between bars and infragravity waves is performed combining laboratory experiments and numerical modeling. Experiments are carried out in a wave flume with a barred profile. The Boussinesq fully-nonlinear model SERR1D is validated with the laboratory data and a sensitivity analysis is performed next to study the influence on the infragravity wave dynamics of bar amplitude and location, and swash zone slope. A novel technique of incident and reflected motions separation that conserves temporal characteristics is applied. We observe that changing bar characteristics induces substantial variations in trapped energy. Interestingly, a modification of swash zone slope has a large influence on the reflected component, controlling amplitude and phase time-lag, and consequently on the resonant pattern. Variations of trapped infragravity energy induced by changes of swash zone slope reach 25 %. These changes in infragravity pattern consequently affect short-wave dynamics by modifying the breakpoint location and the breaking intensity. Our conceptual investigation suggests the existence of a morphological feedback through the action of evolving morphology on infragravity structures which modulates the action of short-waves on the morphology itself.
(pp. currents.24, 28/10/2026)
LEGOS, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, PUC, UTFSM, LEGI, UJF, Grenoble INP, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Climatically-controlled siliceous productivity in the eastern Gulf of Guinea during the last 40 000 yr
Opal content and diatom assemblages were analysed in core GeoB4905-4 to reconstruct siliceous productivity changes in the eastern Gulf of Guinea during the last 40 000 yr. Opal and total diatom accumulation rates presented low values over the considered period, except during the Last Glacial Maximum and between 15 000 calendar years Before Present (15 cal. ka BP) and 5.5 cal. ka BP, the so-called African Humid Period, when accumulation rates of brackish and freshwater diatoms at the core site were highest. Conversely, accumulation rates of windblown diatoms exhibited an opposite pattern with higher values before and after the African Humid Period and greatest values during Heinrich Events, the Younger Dryas and since 5.5 cal. ka BP. Our results demonstrate that siliceous productivity in the eastern Gulf of Guinea was directly driven by the nutrient load from local rivers, whose discharges were forced by precipitation changes over western Equatorial Africa and/or modification of the fluvio-deltaic systems forced by sea level changes. Precipitation in this region is controlled by the West African monsoon which is, in turn, partly dependent on the presence and intensity of the Atlantic Cold Tongue (ACT). Our results therefore suggest that the ACT was weakened, warmer trade winds were less vigorous, and cloud convec-tion and precipitation were greater during the AHP though centennial-to-millennial timescale dry events were observed at ∼10 cal. ka BP, ∼8.5 cal. ka BP and ∼6 cal. ka BP. Conversely , the ACT was more intense, trade winds were more vigorous and African climate was more arid during H1, the Younger Dryas and after 5.5 cal. ka BP into the present.
(Climate of the Past. vol. 8, n° 1814-9324, pp. 415-431, 28/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IACT, CSIC, UGR, CAU